Preheat the oven to 350F (180C) and line cookie sheets with parchment paper or silicone baking mats.
Add the freeze dried berries to a food processor and pulse until they're a fine powder. Measure out 1/3 cup for the cookie dough. Any remaining powder can be used for rolling the cookies in with sugar.
In a medium bowl, whisk together the flour, cornstarch, baking soda and salt. Set aside.
In a large bowl, beat together the butter, 1 1/4 cup granulated sugar and 1/3 cup freeze dried strawberries until cremed.
Add in the egg, additional egg yolk, vanilla and food coloring to the butter mixture. Beat until combined. Note: for bright pink cookies like the ones pictured, I added 3-4 drops of concentrated red gel food coloring. Without food coloring, the cookies will be pale pink.
Add the dry ingredients into the butter mixture and mix together, starting with the mixer on a low speed, until incorporated.
Mix in the milk. Give the dough a squeeze between your fingers. If the dough is sticking to your fingers, mix in 1 more tablespoon of flour.
On a small plate, mix together the 1/3 cup granulated sugar and any remaining pulverized freeze dried berries. Scoop the dough into balls with about 1 to 1 1/2 tablespoons of dough each - they should be a little smaller than a golf ball (I used a cookie scoop for this). Roll the dough balls in the strawberry sugar mixture. Note: If you've used all the freeze dried berries, simply roll the dough balls in 1/3 cup sugar.
Place the cookie dough balls about 2 inches apart on the lined cookie sheets. Bake 1 sheet at a time in the middle of the preheated oven. The cookies will bake for about 9-11 minutes, or until the tops look just set.